Roadways, sidewalks, bridges, buildings, water ducts, reservoirs, and other infrastructure and structural components are often manufactured from cementitious composites such as concrete. Concrete includes cement and other things, such as various aggregates and paste. Aggregates include small materials such as sand, gravel or crushed stone. Often, the paste that holds the aggregates together is water and Portland cement. Portland cement is a generic term for the most prevalent type of cement. Cement typically makes up from 10% to 15% of the total mass of concrete. Portland cement is a type of hydraulic cement, which means that when water is added, a chemical reaction is started that causes the cement to harden and set, holding the aggregates together in a rocklike mixture—concrete. Before the concrete is allowed to harden, the concrete mix is poured into a mold so that it will harden into the desired shape. The Portland cement is typically made from a combination of calcareous material (usually limestone or other calcium carbonate-based materials) and argillaceous material (usually siliceous and aluminous minerals containing substantial amounts of clay-like components).
High strength cement-based materials such as macro-defect-free (MDF) cements are being developed for use in many applications that have not been possible with traditional cement and concrete technology. MDF refers to the absence of relatively large voids or defects which are usually present in conventional mixed cement pastes because of entrapped air, inadequate dispersion, and porosity that develops as water soaks into cement particles and aggregate and leaves behind voids. Such voids and defects limit the strength of conventional Portland cement. MDF cement is a polymer-cement composite. The polymer and cement react synergistically to create a unique microstructure with distinct characteristics. The base polymer of the cementitious composite of MDF cement is a water-dissolvable polymer, such as polyvinyl alcohol (PVOH). High shear mixing that is akin to rubber mixing is applied to the mixture during production. MDF cements are characterized by very high flexural strength and a high modulus of elasticity. Flexural strength, also known as modulus of rupture, bend strength, or fracture strength, is a mechanical parameter that is defined as a material's ability to resist deformation under load. Modulus of elasticity is a number that measures an object or substance's resistance to being deformed elastically when a force is applied to it. These desirable characteristics are thought to be a result of the elimination of the majority of the voids that are in typical cementitious composites caused by air entrapped during the mixing, and the elimination of the majority of pores and capillaries that are formed when water is desiccated during cement hydration. Similar to traditional concrete recipes, a wide range of ingredients may be added to the MDF cement to act as plasticizers, accelerators, retardants, and water-reducing agents. Called admixtures, these additives can be used to increase the workability of a cement mixture, the strength of the cement after application, the amount of time the cement will take to harden and achieve full strength, and other desirable properties. The proportions of the various raw materials that go into the cement must be carefully controlled and measured in order to obtain a finished product with the desired characteristics.
Japanese published application no. JP11314643 of Hokushin, published on Nov. 16, 1999, discloses a cementitious composite packet in which the materials needed to produce the finished cement are placed in powdery-granular form into a bag made of water-soluble plastic film. The quantities of the powdery-granular materials are provided in the bags. A problem not addressed by the Japanese published application no. JP11314643 is the potential difficulty in providing the precise amount of water that is needed when mixing one or more bags of the cementitious composite in order to achieve desired mechanical characteristics and setting times for the cement.
The disclosed compositions are directed to overcoming one or more of the problems set forth above and other problems of the prior art.